Control system for heliostats and method

Abstract

A control system and method for a heliostat or a system of heliostats which operates to maintain the sunbeam properly centered with respect to an associated tracking head and tracks the sun for proper elevational and azimuthal orientation of the heliostat. The tracking date is stored in memory and utilized to reset the heliostat at night for proper orientation during the next days tracking and/or for proper orientation during sunless periods of the day. Each heliostat is therefore self-tracking.

I claim: 
     
       1. A control system for sequentially controlling the movement of a plurality of heliostats employed in combination with a solar receiver, comprising: means for controlling the elevational rotational orientation of each heliostat;   means for controlling the azimuthal rotational orientation of each heliostat;   a tracking mirror operatively associated with each heliostat;   tracking means operatively associated with the solar receiver and arranged to receive reflected sun rays from each tracking mirror sequentially, said tracking means including transducer means for generating signals indicative of both the relative elevational and azimuthal rotational orientation of the heliostat being sequenced; and   control means connected sequentially to the means for controlling the elevational rotational orientation of each heliostat, the means for controlling the azimuthal rotational orientation of each heliostat, and the tracking means, said control means receiving the signals generated by the transducer means and generating control signals for activating the means for controlling the elevation rotational orientation of each heliostat, and the means for controlling the azimuthal rotational orientation of each heliostat, to thereby adjust the relative elevational rotational and relative azimuthal rotational position of each heliostat, so that sun rays reflected by the heliostat are received by the solar receiver, wherein:   (i) the transducer means comprises four solar sensors arranged in any array on the perimeter of the image of a sun ray received by the tracking means, such that two of said sensors are displaced along a horizontal axis to generate a signal related to aximuth orientation of the heliostat being sequenced and the other two of said sensors are displaced along a vertical axis to generate a signal related to elevational orientation of the heliostat being sequenced;   (ii) said control means including:   a tracking generator board connected to the tracking means;   a power board connected to the tracking generator board, to the means for controlling the elevational rotational orientation of each heliostat, and to the means for controlling the azimuthal rotational orientation of each heliostat;   a commutator board connected to the tracking generator board and to the power board; and   a system clock connected to the tracking generator board and to the commutator board;   (iii) the tracking generator board when activated by the system clock generates tracking drive activation signals from the transducer generator signals, said tracking drive activation signal being applied to said power board which generates the control signal for activating the means for controlling the elevational rotational orientation of each heliostat and the means for controlling the aximuthal rotational orientation of each heliostat; and   (iv) the commutator board controls the generation of said tracking drive activation signal by the tracking generator board in sequence among the heliostats.   
     
     
       2. A control system for sequentially controlling the movement of a plurality of heliostats employed in combination with a solar receiver, comprising: means for controlling the elevation rotational orientation of each heliostat;   means for controlling azimuthal rotational orientation of each heliostat;   a tracking mirror operatively associated with each heliostat;   tracking means operatively associated with the solar receiver and arranged to receive sun rays from each tracking mirror sequentially, said tracking means including transducer means for generating signals indicative of both the relative elevational and azimuthal rotational orientation of the heliostat being sequenced; and   control means connected sequentially to the means for controlling the elevational rotational orientation of each heliostat, the means for controlling the azimuthal rotational orientation of each heliostat, and the tracking means, said control means receiving the signals generated by the transducer means and generating control signals for activating the means for controlling the elevation rotational orientation of each heliostat, and the means for controlling the azimuthal rotational orientation of each heliostat, to thereby adjust the relative elevational rotational and relative azimuthal rotational position of each heliostat, so that sun rays reflected by the heliostat are received by the solar receiver, wherein:   (i) the transducer means comprises four solar sensors arranged in any array on the perimeter of the image of a sun ray received by the tracking means, such that two of said sensors are displaced along a horizontal axis to generate a signal related to azimuthal orientation of the heliostat being sequenced and the other two of said sensors are displaced along a vertical axis to generate a signal related to elevational orientation of the heliostat being sequenced;   (ii) said control means including:   a tracking generator board connected to the tracking means;   a power board connected to the tracking generator board, to the means for controlling the elevational rotational orientation of each heliostat, and to the means for controlling the aximuthal rotational orientation of each heliostat;   a commutator board connected to the tracking generator board and to the power board;   a system clock connected to the tracking generator board and to the commutator board; and   manual control switch means connected to the tracking generator board, the power board and the commutator board; and   (iii) the manual control switch means includes an elevational control switch, an azimuthal control switch and a heliostat selection control switch, the elevational control switch and the azimuthal control switch are connected to the tracking generator board, and the heliostat selection control switch is connected to the power board.   
     
     
       3. A control system for sequentially controlling the movement of a plurality of heliostats employed in combination with a solar receiver, comprising: means for controlling the elevation rotational orientation of each heliostat;   means for controlling the azimuthal rotational orientation of each heliostat;   a tracking mirror operatively associated with each heliostat;   tracking means operatively associated with the solar receiver and arranged to receive reflected sun rays from each tracking mirror sequentially, said tracking means including transducer means for generating signals indicative of both the relative elevational and azimuthal rotational orientation of the heliostat being sequenced;   control means connected sequentially to the means for controlling the elevational rotational orientation of each heliostat, the means for controlling the azimuthal rotational orientation of each heliostat, and the tracking means, said control means receiving the signals generated by the transducer means and generating control signals for activating the means for controlling the elevation rotational orientation of each heliostat, and the means for controlling the azimuthal rotational orientation of each heliostat, to thereby adjust the relative elevational rotational and relative azimuthal rotational position of each heliostat, so that sun rays reflected by the heliostat are received by the solar receiver; and   cover means connected to said control means for covering the tracking mirror, wherein:   (i) the transducer means comprises four solar sensors arranged in any array on the perimeter of the image of a sun ray received by the tracking means, such that two of said sensors are displaced along a horizontal axis to generate a signal related to azimuth orientation of the heliostat being sequenced and the other two of said sensors are displaced along a vertical axis to generate a signal related to elevational orientation of the heliostat being sequenced;   (ii) said control means including:   a tracking generator board connected to the tracking means;   a power board connected to the tracking generator board, to the means for controlling the elevational rotational orientation of each heliostat, to the means for controlling the azimuthal rotational orientation of each heliostat and to the cover means for each tracking mirror;   a commutator board connected to the tracking generator board and to the power board; and   a system clock connected to the tracking generator board and to the commutator board.   (iii) the tracking generator board comprises a first pulse delay generator which receives pulses from the system clock and generates a measuring activation signal pulse; and   (iv) the power board receives the measuring activation signal pulse and generates a control signal which is applied to the cover means for moving the cover means relative to the tracking mirror.   
     
     
       4. The control system as defined in claim 1, wherein the control means further includes: a memory board connected to the tracking generator board, and wherein the tracking generator board further comprises:   an azimuth sun energy detection circuit connected to the azimuth orientation solar sensors;   an elevation sun energy detection circuit connected to the elevation orientation solar sensors; and   a tracking generator circuit connected to the azimuth sun energy detection circuit, the elevation sun energy detection circuit, the memory board and the power board, for switching between a sun track mode of operation with the azimuth sun energy detection circuit and the elevation sun energy detection circuit connected to the power board, and a memory track mode of operation with the memory board connection to the power board.   
     
     
       5. A control system for sequentially controlling the movement of a plurality of heliostats employed in combination with a solar receiver, comprising: means for controlling the elevation rotational orientation of each heliostat;   means for controlling the azimuthal rotational orientation of each heliostat;   a tracking mirror operatively associated with each heliostat;   tracking means operatively associated with the solar receiver and arranged to receive reflected sun rays from each tracking mirror sequentially, said tracking means including transducer means for generating signals indicative of both the relative elevational and azimuthal rotational orientafion of the heliostat being sequenced; and   control means connected sequentially to the means for controlling the elevational rotational orientation of each heliostat, the means for controlling the azimuthal rotational orientation of each heliostat, and the tracking means, said control means receiving the signals generated by the transducer means and generating control signals for activating the means for controlling the elevation rotational orientation of each heliostat, and the means for controlling the azimuthal rotational orientation of each heliostat, to thereby adjust the relative elevational rotational and relative azimuthal rotational position of each heliostat, so that sun rays reflected by the heliostat are received by the solar receiver, wherein:   (i) the transducer means comprises four solar sensors arranged in any array on the perimater of the image of a sun ray received by the tracking means, such that two of said sensors are displaced along a horizontal axis to generate a signal related to azimuth orientation of the heliostat being sequenced and the other two of said sensors are displaced along a vertical axis to generate a signal related to elevational orientation of the heliostat being sequenced; and   (ii) said control means including:   a tracking generator board connected to the tracking means;   a power board connected to the tracking generator board, to the means for controlling the elevational rotational orientation of each heliostat, and to the means for controlling the azimuthal rotational orientation of each heliostat;   a commutator board connected to the tracking generator board and to the power board;   a system clock connected to the tracking generator board and to the commutator board; and   a memory board connected to the tracking generator board, said memory board including: a counter; a memory for storing azimuth data generated by the counter; a memory for storing elevation data generated by the counter; and switch means for switching the memories between read and write modes.   
     
     
       6. The control system as defined in claim 1, wherein the commutator board includes a counter, and a decoder connected at its input to the counter and at its output to the power board and the manual control switch, and wherein the control means further includes: zero out switch connected to the memory board counter and the commutator board counter.   
     
     
       7. A control system for sequentially controlling the movement of a plurality of heliostat employed in combination with a solar receiver, comprising: means for controlling the elevation rotational orientation of each heliostat;   means for controlling the azimuthal rotational orientation of each heliostat;   a tracking mirror operatively associated with each heliostat;   tracking means operatively associated with the solar receiver and arranged to receive reflected sun rays from each tracking mirror sequentially, said tracking means including transducer means for generating signals indicative of both the relative elevational and azimuthal rotational orientation of the heliostat being sequenced;   control means connected sequentially to the means for controlling the elevational rotational orientation of each heliostat, the means for controlling the azimuthal rotational orientation of each heliostat, and the tracking means, said control means receiving the signals generated by the transducer means and generating control signals for activating the means for controlling the elevation rotational orientation of each heliostat, and the means for controlling the azimuthal rotational orientation of each heliostat, to thereby adjust the relative elevational rotational and relative azimuthal rotational position of each heliostat, so that sun rays reflected by the heliostat are received by the solar receiver; and   cover means connected to said control means for covering the tracking mirror, wherein:   (i) the transducer means comprises four solar sensors arranged in any array on the perimeter of the image of a sun ray received by the tracking means, such that two of said sensors are displaced along a horizontal axis to generate a signal related to azimuth orientation of the heliostat being sequenced and the other two of said sensors are displaced along a vertical axis to generate a signal related to elevational orientation of the heliostat being sequenced;   (ii) said control means including:   a tracking generator board connected to the tracking means;   a power board connected to the tracking generator board, to the means for controlling the elevational rotational orientation of each heliostat, to the means for controlling the azimuthal rotational orientation of each heliostat and to the cover means for each tracking mirror;   a commutator board connected to the tracking generator board and to the power board; and   a system clock connected to the tracking generator board and to the commutator board; and   (iii) the power board includes a power module circuit for each heliostat, wherein each power module circuit receives an azimuth input signal, an elevation input signal, and a mirror motor input signal from the tracking generator board and a heliostat selector input signal from the commutator board, each power module circuit including a stepping motor for elevation control, a stepping motor for azimuth control, a motor for mirror cover control and a switch circuit for switching between the respective motors.